Centrifugal blower wheel and method of construction



June 23, 1964 v. N. DELANEY ETAL CENTRIFUGAL BLOWER WHEEL AND METHOD OF CONSTRUCTION 2 Sheets-Sheet 1 Filed Feb. 18, 1965 INVENTOR VINCENT N. DELANEY KENNETH A. MERz BY n ATTORNEYS J1me 1964 v. N. DELANEY ETAL 3,133,319

CENTRIFUGAL BLOWER WHEEL AND METHOD OF CONSTRUCTION Filed Feb. 18, 1963 2 Sheets-Sheet 2 United States Patent ration of Connecticut Filed Feb. 18, 1963, Ser. No. 259,033 10 Claims. (Cl. 238-134) This invention relates to centrifugal blower wheels and more particularly to a novel construction which permits the blade strip to be readily assembled with its associated end support members.

An object of the present invention is to provide a blower wheel having a blade strip which has been longitudinally shortened prior to assembly and which blade strip is nevertheless well adapted to being supported by end support members of simplified construction.

Another object of the present invention is to provide a blower wheel in which the spacing between blades is reduced by tucks taken in portions of the marginal sections of the blade strip, which marginal sections are nevertheless well adapted to receive the end support members assembled therewith in a single economical spinning or bending operation.

Another object of the present invention is to provide a method of making a blower wheel of the type referred to wherein the tucks are formed in a particular manner to facilitate assembly of the blade strip with end support members.

The drawings show a preferred embodiment of the invention and such embodiment will be described, but it will be understood that various changes may be made from the construction disclosed, and that the drawings and description are not to be construed as limiting the scope of the invention, the claims forming a part of this specification being relied upon for that purpose.

Of the drawings:

FIG. 1 is a plan view of a blade strip illustrating various steps in the method of the present invention.

FIG. 2 is a side view partly in section of the blade strip of FIG. 1.

FIG. 3 is a fragmentary top view of the assembled blower wheel.

FIG. 4 is a side view of the wheel of FIG. 3.

FIG. 5 is a sectional view along the line 55 of FIG. 3 with one end support member shown prior to assembly.

FIG. 1 shows an elongated blade strip of the present invention prior to being coiled into an annulus and assembled with its end support members to produce a blower wheel. A series of transversely extending blades 12, 12 are cut in a center section 14 of the generally flat sheet metal blade strip, to be bent towards the vertical as shown in FIG. 2 and formed into an airfoil cross section well adapted to moving a fluid such as air. These blades may be constructed by any convenient method, the particular method used forming no essential part of the present invention.

As shown, two oppositely disposed marginal sections 16, 16 are provided on either side of the center or bladed section 14 and one step in producing the blade strip involves cutting a series of notches 18, 18 at spaced locations along outer portions 20, 20 of these marginal sections. The said spaced locations correspond at least approximately to the interblade openings 22, 22 and each of these notches is preferably tapered in plan form, with an inner end 24 which is wider than an outer end 26 thereof. Each notch 18 is also shaped so that an outer part 28 of said outer portion 20 defines opposite parallel edges 29, 29 of each notch for a purpose which will be made clear hereinafter.

3,138,319 Patented June 23, 1964 Another step in producing a blade strip of the present invention is to bend the outer parts 28, 28 of the notched marginal sections 16, 16 along longitudinal lines 30, 30 to provide upstanding flanges 32, 32 along the said marginal sections. The longitudinal bend lines 30, 30 are located at the junctions between the outer parts 28, 28 of the outer portions 20, 20 and inner parts 33, 33 thereof thus achieving a transverse spacing between the flanges 32, 32 and the inner annular portions 34, 34 for a purpose which will be made clear hereinafter. The tapered portions of the notches 18, 18 will be seen to lie wholly in the inner annular parts 33, 33 while the portions of the notches with the parallel edges 29, 29 lie wholly in the outer parts 28, 28 or flanges 32, 32.

Still another and a most important step in constructing the blade strip 10 is to decrease the longitudinal spacing between blades in order to improve the air-moving ability of a blower wheel of the present invention. In the blade strip described hereinabove, inner portions 34, 34 of the marginal sections 16, 16 between the ends of the blade openings 22, 22 and the inner ends of the notches 18, 18 are available for gathering into a series of tucks or the like. As shown these tucks form a series of equally spaced generally U-shaped transversely offset parts 36, 36, FIG. 2.

It will be apparent from FIGS. 1 and 2 that the U- shaped tucks or projections 36, 36 of the marginal sections 16, 16 shorten the blade strip achieving the aforesaid decreased blade spacing. It will also be apparent that the parallel notch edges 29, 29 provide a convenient stop in the strip shortening operation and permit the spacing between blades to be accurately controlled. In consequence, snbsequent assembly and balancing of the completed blower wheel is greatly facilitated.

Another advantage flowing from the aforementioned parallel edge and dovetailed shape of the notches 18, 18 lies in the greater bend radius permitted in forming the U-shaped offsets 36, 36. As best shown in FIG. 2, a desirably large bend radius is obtainable at the base as well as the apex of each offset part or tuck 36.

A final and a most important step carried out on the fiat blade strip 10 involves the bending of the U-shaped oifset parts 36, 36 inwardly from their generally normal initial orientation to an inclined position whereby the transverse spacing between said offset parts and the flanges 32, 32 is further increased.

Prior to final assembly of the blower wheel, the blade strip is rolled or coiled into an annulus or generally cylindrical shape and the end portions (not shown) are brought into end-to-end engagement with one another. When so arranged the center section 14 of the blade strip is annular in shape as are the oppositely disposed marginal sections 16, 16. The blades 12, 12 extend axially and are circumaxially spaced with the U-shaped parts or tucks 36, 36 projecting generally radially outwardly. The offsets or tucks 36, 36 are axially spaced from the flanges 32, 32 of the marginal sections and are bent axially inwardly to an inclined position between radial and axial planes, FIG. 5.

A further step in producing a blower wheel of the present invention is to provide a pair of generally annular support members 38, 38 as shown in FIGS. 3, 4 and 5. As shown in FIG. 5 a peripheral portion of each support member 38 is preferably provided with an inner cylindrical bearing surface 40 adapted to fit snugly against the 8.? corresponding flange 32 on the blade strip and a short radially inwardly extending annular flange 48 defining the other leg of the L and connecting the flange 46 to the said bearing surface 40.

In assembling a wheel of the present invention the outermost flange 46 is spun over the blade strip flange 28 as shown in FIG. producing an annular connection which is U-shaped in cross section with the inner and Outer legs spaced axially and extending generally radially inwardly. The said U-shaped sections are disposed respectively about and in holding engagement with the flanges 32, 32 of the corresponding marginal strip sections 16, 16 with each inner leg 46 being disposed between the U-shaped offset parts or tucks 36, 36 and the flanges 32, 32. Thus, the blade strip marginal sections are securely held in a clamping engagement by the end support members to provide a blower wheel which exhibits a high degree of structural integrity.

The provision of the offset parts or tucks 36, 36 in axially spaced relationship with the flanges 32, 32 and in an inwardly inclined attitude results in ample clearance for the flanges 46, 46 and the spinning tools and greatly facilitates the spinning operation. Additionally, the small offset parts or tucks 36, 36 can serve as a balancing means, i.e., selective removal of the tucks as by clipping can be accomplished to balance the finished wheel. Still further, the wheel of the present invention is found to provide a high degree of efficiency in operation. The offset parts or tucks 36, 36 extend over the interblade openings and are believed to reduce fluid circulation in an area where circulation is detrimental to wheel performance.

The invention claimed is:

V l. The combination in a centrifugal blower wheel of a sheet metal blade strip arranged in a generally cylindrical configuration and comprising annular center and opposite marginal sections, said center section comprising a plurality of circumaxially spaced axially extending fluid moving blades and each of said marginal sections comprising axially adjacent inner and outer annular portions, said inner annular portions being disposed adjacent the ends of the blades and interblade openings and having small generally U-shaped offset parts which are respectively at least approximately aligned axially with said openings and which permit close circumaxial spacing of the blades, said outer annular portions each having an annular series of inwardly extending notches respectively at least approximately aligned axially with said offset parts of said inner annular portions, and said outer annular portions further having inner and outer annular parts the former of which lie substantially in a cylindrical surface and the latter of which extend outwardly therefrom and lie substantially in a radial plane spaced axially from said offset parts, and oppositely disposed annular end support members associated respectively with said marginal strip sections and each comprising a peripheral portion of generally U-shaped cross section with inner and outer legs spaced axially and extending generally radially inwardly, said U-shaped sections being disposed respectively about and in holding engagement with the said outer annular parts of the corresponding marginal strip sections, and each inner leg being disposed between said offset parts and said outer annular part of the marginal section.

2. The combination in a centrifugal blower wheel as set forth in claim 1 wherein said generally U-shaped offset parts of said inner annular portions of the marginal sections project generally radially outwardly with respect to said adjacent outer annular portions of the marginal sections.

3. The combination in a centrifugal blower wheel as set forth in claim 2 wherein said offset parts are inclined between radial and axial planes and away from said outer annular portions.

4. The combination in a centrifugal blower wheel as set forth in claim 3 wherein each of said notches has an inner end of greater width than its outer end.

5. The combination in a centrifugal blower wheel as set forth in claim 4 wherein each of said notches has an outer portion with substantially parallel side walls and an inner portion generally dovetailed in configuration.

6. The method of forming a centrifugal blower wheel comprising the steps of providing an elongated blade strip including a longitudinally extending center section comprising a plurality of longitudinally spaced transversely extending fluid moving blades and also including oppositely disposed marginal sections connected to the ends of said blades and extending longitudinally of said strip, notching the outer portions of said marginal sections at spaced longitudinal positions in approximate transverse alignment with the openings between said blades, bending outer parts of the notched marginal sections along longitudinal lines to provide upstanding flanges along said marginal sections, transversely offsetting parts of the continuous inner portions of said marginal sections between the inner ends of said notches and the outer ends of said blade openings whereby to provide two rows of longitudinally spaced projections spaced transversely from the flanges and to decrease the longitudinal spacing between blades, forming said blade strip into a generally cylindrical shape so that said flanges project generally radially outwardly, providing blower wheel end support members with peripheral portions extending radially outwardly beyond said flanges, and forming the peripheral portions of said support members to assembled positions wherein they extend axially inwardly and then radially inwardly around and in embracing relationship with said flanges and between the flanges and said transversely offset parts.

7. The method as set forth in claim 6 wherein the step of transversely offsetting parts of the continuous inner portions of said marginal sections includes the bending of said offset parts generally in the same direction as the flanges to a small generally U-shape and the displacement of the same away from the adjacent flanges.

8. The method as set forth in claim 7 wherein the step of notching the outer portions of the marginal sections is carried out in such manner as to provide notches which are wider at their inner ends than at their outer ends.

9. The method as set forth in claim 7 wherein the end support members are so formed as to provide generally cylindrical bearing surfaces within and in engagement with the strip marginal sections.

10. The method as set forth in claim 7 wherein the end support members are preformed with short axially inwardly extending annular flanges, and wherein said flanges are disposed about the corresponding blade strip flanges and spun generally radially inwardly to positions between the blade strip flanges and said offset parts.

References Cited in the file of this patent UNITED STATES PATENTS 2,242,586 Marbach May 20, 1941 2,291,480 Marbach July 28, 1942 2,470,966 Abbott et al. May 24, 1949 2,537,805 Wilken Jan. 9, 1951 2,684,521 Morrison July 27, 1954 2,833,464 Sharp May 6, 1958 2,932,446 Zaro Apr. 12, 1960 

1. THE COMBINATION IN A CENTRIFUGAL BLOWER WHEEL OF A SHEET METAL BLADE STRIP ARRANGED IN A GENERALLY CYLINDRICAL CONFIGURATION AND COMPRISING ANNULAR CENTER AND OPPOSITE MARGINAL SECTIONS, SAID CENTER SECTION COMPRISING A PLURALITY OF CIRCUMAXIALLY SPACED AXIALLY EXTENDING FLUID MOVING BLADES AND EACH OF SAID MARGINAL SECTIONS COMPRISING AXIALLY ADJACENT INNER AND OUTER ANNULAR PORTIONS, SAID INNER ANNULAR PORTIONS BEING DISPOSED ADJACENT THE ENDS OF THE BLADES AND INTERBLADE OPENINGS AND HAVING SMALL GENERALLY U-SHAPED OFFSET PARTS WHICH ARE RESPECTIVELY AT LEAST APPROXIMATELY ALIGNED AXIALLY WITH SAID OPENINGS AND WHICH PERMIT CLOSE CIRCUMAXIAL SPACING OF THE BLADES, SAID OUTER ANNULAR PORTIONS EACH HAVING AN ANNULAR SERIES OF INWARDLY EXTENDING NOTCHES RESPECTIVELY AT LEAST APPROXIMATELY ALIGNED AXIALLY WITH SAID OFFSET PARTS OF SAID INNER ANNULAR PORTIONS, AND SAID OUTER ANNULAR PORTIONS FURTHER HAVING INNER AND OUTER ANNULAR PARTS THE FORMER OF WHICH LIE SUBSTANTIALLY IN A CYLINDRICAL SURFACE AND THE LATTER OF WHICH EXTEND OUTWARDLY THEREFROM AND LIE SUBSTANTIALLY IN A RADIAL PLANE SPACED AXIALLY FROM SAID OFFSET PARTS, AND OPPOSITELY DISPOSED ANNULAR END SUPPORT MEMBERS ASSOCIATED RESPECTIVELY WITH SAID MARGINAL STRIP SECTIONS AND EACH COMPRISING A PERIPHERAL PORTION OF GENERALLY U-SHAPED CROSS SECTION WITH INNER AND OUTER LEGS SPACED AXIALLY AND EXTENDING GENERALLY RADIALLY INWARDLY, SAID U-SHAPED SECTIONS BEING DISPOSED RESPECTIVELY ABOUT AND IN HOLDING ENGAGEMENT WITH THE SAID OUTER ANNULAR PARTS OF THE CORRESPONDING MARGINAL STRIP SECTIONS, AND EACH INNER LEG BEING DISPOSED BETWEEN SAID OFFSET PARTS AND SAID OUTER ANNULAR PART OF THE MARGINAL SECTION. 